Originally Posted by JamesMio

Looks like a good route to me - happy to offer any help along the D&G / Borders bits. The A713 CD - Ayr is a good road, but the Crocketford - Newton Stewart bit is sublime! The road between Newton Stewart and Girvin is good fun too (few potholes to look out for, but that's just D&G for you I'm afraid).

Another possible alternative to skimming around Glasgow could be to get the ferry between Gourock & Dunoon, then heading North and re-joining your route at Arrochar.?